All sorted! Combination of the above. Checked the lever - all good. Loosened the latch a tad and then had a mate push down on the bonnet while I pulled lever - success. A good clean and a heap of new grease and all seems sweet. Thanks guys!
I had the same problem, none of the above methods worked and i couldnt unscrew that thing. So in rage i kicked the bumper and bam the bonnet popped open lol
24.05.14 - While washing the car I noticed the springy thing was loose so I tighten it and then after testing the catch, the bonnet worked fine but after an 700 klm trip away the bonnet won't open.
Slapping bonnet wont work and the screw part isn't budging and the catch lever is fine although it is stretchy.
Better get busy looking up other past postings on how to correct the problem.